Ioane comes in at blindside flanker and will look to bring his hard-running style to the match.
The other change in the forward pack comes in the front row, where tighthead prop Donald Brighouse gets a start and Hisa Sasagi moves to the bench.
Ioane has been a strong impact player off the bench for Otago for the past two seasons and his toughness will be much appreciated for Otago in what is bound to be a bruising game.
The backs remain the same, coach Tony Brown resisting the temptation to bring Jayden Spence in from the wing and play him in the midfield.
Tony Ensor comes on to the bench to replace Marshall Suckling, while Nahlia Dawai will make his debut for Otago if he gets off the bench.
Allan suffered a heavy blow to the head early in the second half in the match against Counties-Manukau and left the field with concussion. He has been tested during the week and a decision has been made that he is not right for the match tomorrow.
Brighouse has impressed coming off the bench in the first two matches, and now gets his chance in the starting line-up.
The Otago scrum was under pressure at some stages in the loss to Counties-Manukau and Brighouse will look to strengthen that facet of the blue and golds' game.
Otago assistant coach Phil Young said Brighouse now had the opportunity to make an impact and show some strength at scrum time.
Concerns had been raised over the big prop's playing weight but Young said the coaching staff had no problem with that.
The side had recovered well from the Ranfurly Shield defeat in Pukekohe and was looking forward to taking on neighbour Southland.
''We have taken on some learnings we got from the game in Pukekohe and we have flushed the rest and moved on,'' Young said.
''We are seeing a slightly different style from Southland this year, in that they look to use a bit more width in their play. They have got some pretty exciting backs and a forward pack which has been together for some time. We are expecting it to be a tough game.''
Otago has trained well this week and is looking to win back the Donald Stuart Memorial Trophy which it lost last year in a nailbiter.
Southland will name its team today.
Otago v Southland
Invercargill, tomorrow, 5.35pm
Otago: Trent Renata, Jayden Spence, Michael Collins, Tei Walden, Fa'asiu Fuatai, Hayden Parker, Josh Renton, Charlie O'Connell (captain), James Lentjes, TJ Ioane, Tom Franklin, Joe Latta, Donald Brighouse, Liam Coltman, Aki Seiuli. Reserves: Sam Anderson-Heather, Hisa Sasagi, Jackson Hemopo, Nahlia Dawai, Nick Ealey, Peter Breen, Tony Ensor.
